Who the heck would want to ask me a question? However, I would still be glad to answer any.
Structural Engineering, the bold, sexy profession!
What exactly IS structural engineering, and how does it differ from civil and mechanical engineering?
Does your hatred of architects burn with the fire of a thousand suns? Or does it merely smoulder like BBQ charcoal, only flaring up at the approach of architectural flesh?
Hodge (structural draftsman)
Structural engineering refer to the art and science of designing constructed systems to resist imposed forces. The most common forces that are resisted include gravity, seismic forces, wind and water. Common materials that are used to resist imposed forces include concrete, steel, wood and masonry.
Structural Engineering is a sub-set of both civil and mechanical engineering. Structural engineers practicing as a sub-set of civil engineering generally design structures used by humans that are exposed to natural forces (buildings, bridges, tunnels and dams), while structural engineers practicing as a sub-set of mechnical engineering design structures used by machines (petro-chemical plants, pressure vessels, tanks, machine frames, etc). There is a lot of overlap between civil, structural and mechnical engineering. Many task could be easily performed by any one of the three.
I myself am a registered professional mechanical engineer and a registred professional structural engineer (with two degrees in civil engineering), and practice in both the civil-structural and mechanical-structural areas.
I hope that answers your questions at least partially.
This may sound silly but what kind of structures do you engineer? Dams, bridges, buildings, etc… (do you specialize)?
I took a training class from a guy that was a concrete engineer (I think that was what he called himself). He worked on big dam projects (damn big projects) and bridges. The stuff he told us was fascinating (sort of wish I had gone into engineering myself).
Depends on the Architect
lionel (Mechanical EIT)
Damn, My previous post was supposed to be after Hodge’s
We have a saying: “it’s not architect, it’s damn architect.”
When I explain what I do to some people, they say, “ohh … so you are an architect.” No, architects draw what the building is to look like. The structural engineer actually draws the plans used by the construction company to building the building. That said, thank god for architects. If structural engineers designed the buildings completely, most cities would look like Hitler’s Atlantic Wall or those depressing communist-block cities of identical concrete low-rise buildings.
About frost heave: I relocated a fence recently, and was afraid that the concrete around the posts would be buried 24-36" under the surface. Everywhere I checked, the sites said that to prevent frost heave, posts should be set that deep.
I put off pulling the posts because I figured they were deep - too deep.
When I finally did, the cement was about 6-18" down, and then stopped, while the post itself went down about 30-36".
I live in New Jersey.
Q. Is frost heave even an issue with fence posts?
Q. If it is, why did my fence contracter only go 6-8"? (They install thousands of fences a year, and I never see any issues with their jobs)
More concrete buildings than anything else, but I do a little bit of everything except dams.
Dang, a serious question and I can’t answer it. We don’t get a lot of frost heave here in Texas. As a matter of fact, we don’t get frost here.
A structural engineer must understand his limitations and not give advice outside their area of expertise as normally lives are at stake. Seriously. A structural engineer’s error killed about 150 people in the Kansas City Hyatt Collapse in 1983.
My username would make it obvious to anyone in the biz.
Personally, my burning hatred of architects is confined to specific individuals.
Mechanical Engineers (the HVAC kind) I hate in boxcar lots. Always wanting to put holes in things at the last minute.
To emphasize what culture says above, I present the following joke:
Do you know what a bench is?
It’s a swing designed by a structural engineer.
Right, I am dealing with a 19 foot deep transfer girder that is cracking. We tear into the structure and find SIX LARGE HAVC PENETRATIONS through the girder that are nowhere on the structural plans. Die HVAC people, DIE!
I was watching the crappy '70s remake of King Kong this weekend, and I was wondering: could Kong have climbed the World Trade Center? Now that we all know exactly how the towers were constructed, I thought, “Hmmm . . . The windows were probably just the right size for finger-grips, assuming he could break the glass and Jessica Lange didn’t impede his progress. But wouldn’t the pre-fab exterior panels just have peeled off with the weight of a giant ape climbing them?”
Now, the Empire State Building: there’s a structure that could withstand both a plane crash and a giant ape!
Well, if you guys wouldn’t put those darn beams and girders in inconvenient places, we wouldn’t have to penetrate them. 
Besides, you structural engineers always take up all of the above ceiling space where I have to design the ducts about 1” deep.
I’m not an engineer, but frost heave is always an issue with anything set in the ground. In my neck of the woods we have to dig about 4’-0" deep for frost protection. That said, fences are forgiving and are able flex quite a bit so may not need to be set so low. However, I remember an engineer telling me about a case where ice constricted about a fence post and effectively popped it out of the ground. He said it acted like a giant sphincter.
Fenceposts ARE subject to frost heave, but the frost depth you found is for buildings, so it’s the “50-year” frost. Basically, that means there’s a 2% probability of there being frost deeper than that in a 50 year period (the concept is the same for “100 year storms”). No wooden fence is going to last 50 years, so it’s a good gamble not to go that deep.
Chances are that whoever installed your fence didn’t know that, and was just installing it the way they’ve always done it and not gotten a lot of complaints. What’s bad about what you describe is the direct dirt-to-wood contact. Can you say termites?
culture- Some days I think we could reduce headcount in the HVAC department by leaving an open box of non-Duplo Legos down there.
I have to run, but I’ll check back on this thread in the morning.
1" won’t work? Just how much air do those wage slaves need, anyway? I swear, have you heard the old saw “give and inch …”
Sure, but that’s not including 2" insulation on either side.
Mechanical Structures/Heat Transfer Engineer/CAE Distributor checking in (I know where “Finite Elephant” comes from).
What kinds of analysis packages do y’all (culture and Finite Elephant) use for building construction? Not really looking for names, I’m more curious as to whether you use general purpose packages or more specialized packages that include various modules to eliminate the rigmarole of modeling from scratch. The software I distribute is more geared toward mechanical, aerospace, and electronic components (including semiconductors) and is pretty general purpose, although it does haves its strengths and weaknesses.
Also, regarding building construction, do the various codes and rules of thumb allow you to pass over the majority of analysis that would have to be done otherwise? I assume that’s part of the reason that they’re there.
Being a mechanical engineering analyst, I don’t get irritated if people refer to me as an “architect”; I get annoyed when they refer to me as a “designer”.
Whoo! Geek talk!